This invention relates to a passive RF information tag which provides status reports through a varying output.
Informational tags and RF transmitters are used in many applications. A first basic type of known tag is a so-called xe2x80x9cactivexe2x80x9d tag which includes a power source. An active tag sends out a beacon signal. Such tags are utilized to identify the location of various items which carry the tag. These type tags may be utilized in inventory control, or in location monitoring.
Another type of tag does not include a power source, and does not send out a signal until it is queried by a transmitter. This type of tag is known as a xe2x80x9cpassivexe2x80x9d tag. A passive tag is provided with a resonant circuit that receives a particular signal which activates its circuit. Typically, an RF transmitter sends a coded signal to the passive tag which then actuates the resonant circuit to provide a signal from the passive tag. Known passive tags obtain information from a fixed memory, and provide that information to the transmitter/receiver which has queried the tag. This type of system is utilized in identification applications. As one example, a garbage truck may include the transmitter/receiver, and dumpsters may include the passive tag. The memory in the dumpster tag would tell the transmitter/receiver the owner of the particular dumpster such that appropriate billing can be made.
The transmitter sends a signal to the passive tag which activates the resonant circuit. The passive tag queries the memory and sends a signal to the transmitter. The transmitter/receiver is then able to identify the owner of the dumpster carrying the tag.
These types of tags are being utilized in more and more applications. However, these types of tags have never been utilized to provide status or variable information.
More and more vehicle diagnostic systems are being provided by electrical components. Vehicle systems monitor brake wear, the amount of movement of an axle, such as an odometer application, the bumps experienced by an axle, etc. These types of diagnostic systems provide a simple electrical signal that is indicative of a problem, or provides information relative to how far the vehicle may have traveled, etc. These types of systems have never been used with the above described tag technology.
In a disclosed embodiment of this invention, a passive RF tag transmits a variable signal that provides information with regard to one or more systems associated with the tag. Preferably, the tag is a passive tag, and the passive tag is provided with a plurality of inputs. The passive tag is preferably associated with a vehicle, and several inputs are preferably diagnostic information from the vehicle.
As one example, a plurality of inputs to the passive tag may be in the form of switches which are either on or off. Thus, the passive tag will see a plurality of digital bits of information.
A switch associated with a brake wear lining may be actuated once a particular amount of brake wear has been experienced. Brake wear systems are known which provide an electronic signal when a predetermined amount of wear has occurred. The brake wear systems are known, and form no part of this invention. If the signal then actuates a switch to change the associated digital information from a zero to a one, the passive tag would then transmit the one to the querying transmitter/receiver. Similar systems may be associated with an accelerometer for monitoring bumps experienced by an axle, etc. Again, the diagnostic systems are known, it is the use of a tag to transmit the information which is inventive. The passive tag then stores these varying signals associated with each of the switches.
When the transmitter/receiver queries the passive tag, the digital information provided by the passive tag has now varied to include the switch which has moved to a closed state, and thus supplies a xe2x80x9c1xe2x80x9d as that associated bit. As a worker in this art knows, whether the xe2x80x9conxe2x80x9d switch provides a xe2x80x9c1xe2x80x9d or a xe2x80x9c0xe2x80x9d is of no moment. It is the varying digital information which is the inventive portion of this application.
Other features provided by the passive tag include a stream of digital information that could be indicative of an analog amount. As an example, one of the inputs to the passive tag is associated with an electronic odometer for a particular axle. The use of electronic odometers is known, and forms no portion of this invention. However, the system could provide a output of the amount of travel for a particular axle through this passive tag. The passive tag would query a stored memory that would include information relating to the amount of travel, and could then transmit that information to the transmitter/receiver.
One other application of this invention would include the use of the passive tag to actuate a particular system. In this application, when the passive tag receives the query, and its circuit is actuated, it could first actuate a particular diagnostic system. As an example, a thermometer associated with a particular system could be actuated to provide a temperature measurement. If the temperature measurement exceeds a predetermined temperature, then an associated switch could be actuated. That associated switch would then be part of the output from the passive tag back to the transmitter/receiver.
The present invention provides a very low cost way of transmitting information about varying occurrences. One particularly advantageous application would be to provide information about diagnostic systems associated with a vehicle. The present invention lends itself well to use on vehicles, and thus provides benefits as outlined above and below.
These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.